<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div></div>
    <script>
        var divEle = document.querySelector('div')
        var count = 60;
        divEle.innerHTML = count;
        var timer = setInterval(function(){
            count--;
            if(count>=-60){
                divEle.innerHTML = Math.abs(count)
            }else if(count = -61){
                count = 60
            }
        },100)
    </script>
</body>
</html>